(a) Field of the Invention
This invention relates to a bottle closure, which is useful more particularly for champagne bottles having threaded mouths, and wherein the body of the closure is unitary and is made of plastic and comprises a stopper like sealing shank which penetrates into the neck of the bottle. In this type of bottle closure, the shank runs centrally from the inner surface of the end of the cap, and the internal surface of the wall of the cap comprises a thread with which the external thread of the neck of the bottle can be engaged. The sealing shank projects beyond the area which carries the thread, a bead surrounding the neck of the bottle is provided at the upper end of the neck, and the external thread of the neck is provided between the bead and the upper edge of the neck of the bottle.
(b) Description of Prior Art
Bottle closures provided with screw threads are used for a very wide variety of applications (cf. U.S. Pat. No. 3,074,579; French Published Specification No. 2,306,895 dated November 1976; French Pat. No. 1,030,600 dated June 1953). However, most of these bottle closures are not suitable for champagne bottles.
Bottle closures of this kind are used mainly for small champagne bottles holding 0.2 liters.
One of the disadvantages of known bottle closures (cf. German Printed Publication No. 26 14 538, French Printed Publication No. 2 306 896 dated October 1977) is that they fail to produce the typical "plop", so characteristic of champagne, when the bottle is opened.
In the meanwhile, a bottle closure of the type in question which produces a "plop" when the champagne bottle is opened has become known (EP-B 0 079 552), this bottle closure comprises a sealing rib at the level of the last turn of a multi-start thread or beyond same on the projecting part. The disadvantage of this bottle closure is that, in spite of the relatively costly sealing shank, the "plop" does not always occur. The reason for this is that, when the sealing rib reaches the upper edge of the neck of the bottle, the rib may tilt, so that CO.sub.2 escapes on one side while the rib still maintains a good seal on the other side.
In one known screw closure for a container, it is known to provide a curving sealing shank which does not have a plurality of sealing ribs (German Printed Publication No. 30 08 838 dated October 1980). This closure also has a sealing lip which, in the closed condition, bears upon the upper edge of the container. The disadvantage of this closure is that it cannot produce a "plop" because the sealing shank does not project beyond the last turn of the screw closure.
A similar screw closure, in which the sealing shank is not curved, is also known (German Printed Publication No. 32 18 671 dated November 1983). However, this closure cannot be used for champagne bottles because it does not have a dome shaped cap.